FAMILY LIMNIAD.E — PHYSA. 77 



This singular shell was found by Mr. G. B. Clendining at the Cohoes falls, adhering to 

 stones. I have adopted the name proposed by its discoverer. It\vas alive, and was desti- 

 tute of an opercle. It is supposed by some conchologists to be a young Planorbis, but I 

 cannot learn that it has been found in the intermediate stages. It is placed provisionally here ; 

 but if a perfect animal, must constitute a new genus. I am inclined to suspect that it is the 

 animal described by Say as Bulla fluviatilis. 



Physa cylindrica. 



PLATE V. FIG. 83. 



(STATE COLLECTION.) 



Pi cylindrica. Newcomb, in Uteris. 



Description. Shell remarkably solid, sinistral, cylindrical. Whorls four, rapidly diminish- 

 ing to the subacute apex. Surface moderately smooth and polished, with incremental lines. 

 Suture impressed : outer lip with a sinuous margin, nearly straight, forming an acute angle 

 with the body, effuse beneath ; body-whorl not convex, but rather flattened and cylindrical. 

 Aperture narrow above, moderately dilated and elongated beneath. Columella smooth, arched 

 with a conspicuous callus reflected over the umbilicus. 



Color. Light rusty, or opake rusty white : outer lip with a rusty submargin within. 



Length, 0-5 ; of aperture, 0-35. 



This specimen was communicated by Dr. Newcomb, who obtained it from Red creek, 

 Wayne county. I have received the same shell under the name of P. elliptica, Lea ; but it 

 does not agree with his description. 



Physa elliptica. 



Physa cylindrica. Lea, Trans. Am. Phil. Soc. No. 5, p. 115, pi. 19, fig. 83/ 



Description. Shell sinistral, elliptical, thin and fragile. Spire short, rapidly attenuating 

 to the tip. Whorls four to five, with minute vertical stria?. Outer lip dilated, margined. 

 Color. Reddish brown, translucid ; the apex amber-colored. 

 Length, 0*5; of aperture, 0-4. Diameter, 0-2 nearly. 

 According to Mr. Lea, found in various parts of the State. 



